H.J. Goldsmid. Effect of the scattering law on the maximum Seebeck coefficient. Journal of
Thermoelectricity. 2006, No.2. - p.5-8.
The optimum Seebeck coefficient for an extrinsic thermoelectric material is equal to 200 mkV/K or more. However, such a value of the Seebeck coefficient cannot normally be reached if the energy gap is smaller than about 4kT and, even then, some account has to be taken of the minority carriers. We show here that the maximum value of the Seebeck coefficient for a given energy gap can be substantially increased if ionised-impurity scattering rather than lattice scattering of the charge carriers is predominant. For example, if the electrons and holes have similar properties in a semiconductor with zero energy gap, the maximum Seebeck coefficient can be raised from less than 100 mkV/K to over 200 mkV/K. It is suggested that the required scattering might be achieved by doping the material with equal large concentrations of donors and acceptors. Attention is drawn to an experiment on compensated bismuth that was carried out several years ago and in which a higher Seebeck coefficient was found than that of the pure element. A more substantial increase should be observed in bismuth if donor and acceptor concentrations of the order of 1025 m-3 were employed.
R.R. Kobylyansky. Computer research on transverse thermoEMF in short-circuited thermoelements. Journal of
Thermoelectricity. 2006, No.2. - p.9-15.
Computer model of short-circuited thermoelement (SCTE) is created. Temperature, potential and current distributions are found. Transverse thermoEMF is studied depending on the number of shorting conductors and shorting angle (the angle between axis and conductor). Optimum is revealed on the angular dependence of transverse thermoEMF. Recommendations as to optimization of short-circuited thermoelement are made.
Tosawat Seetawan. Thermoelectric properties of Ag-added NaxCO2O4. Journal of
Thermoelectricity. 2006, No.2. - p.16-21.
Polycrystalline samples of NaxCo2-yAgyO4 (x = 1.5, y = 0, 0.1, 0.2, 0.3, 0.4, 0.5) were prepared by the sintering of the compacted powder precursors synthesized by the polymerized complex (PC) method. The thermoelectric properties were evaluated in the temperature range from room temperature to 973 K. The electrical resistivity and Seebeck coefficient were measured simultaneously using ULVAC ZEM-1 in He atmosphere The thermal conductivity was calculated from the heat capacity, density, and thermal diffusivity measured by the laser flash method using ULVAC TC-7000 in vacuum. The dimensionless figure of merit (ZT) of Ag-added (0.2) sample was higher than that of non-added sample, and reached ZT = 0.12 at 973 K.
Å.I. Rogacheva, A.A. Drozdova. Thermoelectric properties of polycrystalline bismuth-antimony solid solutions. Journal of
Thermoelectricity. 2006, No.2. - p.22-28.
Thermoelectric properties of polycrystalline bismuth-antimony solid solutions in the composition range 0-9 at.% Sb are studied as a function of composition and temperature. As in the case of single crystals, a regular change in the character of temperature dependences of thermoEMF coefficient S and electric conductivity with increasing Sb content caused by band spectrum variations with changed composition is established. Isotherms S are found to be non-monotone, and assumption as to the nature of observed anomalies that should be taken into account in the development of thermoelectric materials based on Bi-Sb solid solutions is made. The values of thermoelectric figure of merit Z for explored polycrystalline Bi-Sb materials are shown to be comparable to Z values of single crystals in the direction, perpendicular to trigonal axis.
A.F. Semizorov. Preparation and properties of single crystals of ZnxCd1-xSb solid solutions. Journal of
Thermoelectricity. 2006, No.2. - p.29-33.
Anisotropy of electric conductivity, thermoelectric coefficient and Hall mobility of single crystals of ZnxCd1-xSb (x=0.05-0.3) solid solutions, grown by zone recrystallization method with the use of single-crystal seeds is studied. Scattering on acoustic phonons and dislocations is shown to be predominant in the temperature range 77-200 K in material under study.
À.À. Àscheulov. Radiation anisotropic opticothermoelements under various optical and thermal conditions. Journal of
Thermoelectricity. 2006, No.2. - p.34-50.
Influence of various thermal conditions on the volt-watt sensitivity of radiation anisotropic opti-cothermoelements under optical transmission, bulk and surface absorption is studied. They are shown to have good prospects for realization of original “transparent wall” method registering radiant flows over wide spectral and power ranges.
Yu.M. Lobunets. Performance analysis of thermoelectric heater in the heat-regenerating circuit. Journal of
Thermoelectricity. 2006, No.2. - p.51-56.
Airflow heat-regeneration circuit using thermoelectric heat pump (THP) is discussed. The performance of the circuit is analyzed and THP design is optimized for real-life operating conditions. It is demonstrated that dependence of THP efficiency upon ambient temperature in the circuit is reduced dramatically thus making high values of average seasonal heating efficiency possible.
Ye.P. Sabo. Mechanisms determining life potential of thermoelectric converters. Journal of
Thermoelectricity. 2006, No.2. - p.57-67.
The main advantage of thermoelectric devices is their long service life which has been demonstrated on many previously developed radioisotope thermoelectric converters. To provide high reliability and life potential of newly developed converters and improve their manufacturing technique, it is important to know their basic expected degradation mechanisms. An attempt is made in this paper to systematize and generalize experience of assuring service life of various-purpose elaborated thermoelectric converters. Results of testing devices and individual units to degradation are represented, and basic engineering solutions aimed at its reduction are given.
S.O. Filin, A. Owsicki. Experimental research on thermoelectric glass door refrigerators. Journal of
Thermoelectricity. 2006, No.2. - p.68-73.
Thermoelectric refrigeration is traditionally applied mainly in portable car coolers and in stationary refrigerators of volume up to 60 litres. Recent progress in the field of the "know-how" of thermoelectric modules and cooling units has enabled the expansion of the application area of thermoelectric refrigeration. In this paper, temperature parameters of a glass door refrigerator were studied for the first time, for different structural variations of a case (change of insulation thickness) and unit (two or three sections, natural or forced air convection in the chamber), at different supply voltages of modules and ventilators. In experimental way, the optimal scheme of an electric power supply and voltage value, corresponding to the lowest average storage temperature, was obtained. The authors’ research proved technical and economic advantages of application of thermoelectric refrigeration in glass door refrigerators of 100 litres volume for the display and storage of food in the temperature range from +2 to +12?C.
V.Ya. Mikhaylovky, L.T. Strutinskaya, E.V. Chaikovskaya. Specific features of heat exchange in thermoelectric generators using organic-fueled flame heat sources. Journal of
Thermoelectricity. 2006, No.2. - p.74-82.
The regularities of heat exchange process and principal features of organic-fueled thermoelectric generator using water cooling are analyzed. The effects of hydrodynamic properties of gas mix-ture, design parameters of hot radiator and the method of heat exchange between hot gases and hot radiator upon power performance of thermoelectric generator are shown.